Following up on a mention in a CW diary, I have been collecting a little documentation on John Fletcher Wyche (1837-1901) of New Iberia - buried at Rose Hill Cemetery in New Iberia - for my files.
Today I found him (reasonably certain) in the CW POW files - NARA CSR-POW, RG 109, Microfilm M598, Roll 75. He signed his parole on 11 June 1865 at New Iberia, indicating his military association as follows -
J. F. Wyche
C.S. E.O. Parish Lafayette
Resident, New Orleans.
I believe that M598_75 is primarily a listing of officer paroles. I am only guessing, but he was probably indicating Confederate States, Engineering Officer for Lafayette Parish. As I can find him on no other military listing or roll, I am assuming that he was a State or Parish Militia staff member with some sort of officer's commission. If he was at Mansfield at all, my guess is that it was probably as a voluntary staff officer for someone like Alfred Mouton (??), and not as a member of a fighting unit. Also, perhaps the "Major" rank is actually a LA Confederate Veterans post-war rank.
Being 5+ years post discussion string, I hope this helps. If you have found anything else on him, I would be grateful to learn anything additional. I obtained 6 US Census documents (1840, 1850, 1860, 1870, 1880 and 1900), an 1860 LA Census listing, some 1860s US IRS listings, and his Find-a-Grave information. As he had 42 slaves in 1860, and appears to have had a plantation of some sort, surprisingly, no LA or US land purchase documentation was found.